Volcanic Bulges Seen With Microwaves

Don’t try this at home. Your microwave oven uses shorter waves than the L-band microwaves that last March scanned the deadly Galeras volcano in Columbia in the greener image above. The other image is in visible light (on a rare clear day in this area). The microwaves are being used by researchers at NASA to study the land surface, among other things, which is particularly useful when you are dealing with an active volcano, like Galeras, which has a recent history of eruptions and is currently at alert level III. In the last two weeks low level seismicity has accompanied small ash and gas plumes rising from the crater.

L-band microwaves are like those used by a car’s GPS receiver. They can be used to penetrate forest canopies to measure the ground below. So rain or shine, forest or no, detecting even the small changes in the land surface can be done by taking a series of microwave images to see if there is any bulging ground, which is caused by magma rising from below. Such bulges can signal a coming eruption, and so detecting them early is a valuable tool for warning people and saving lives.

The Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) captured the data for the green, false-color microwave image on March 13, 2013, while on board a NASA Gulfstream C-20A aircraft. UAVSAR has a spatial resolution of 6 meters (20 feet) per pixel.

The natural color image was made in 2002 by the Enhanced Thematic Mapper Plus on the Landsat 7 satellite. Landsat 7′s resolution is 30 meters per pixel.

From Discovery News